This application relates to a refrigerant system having a compressor or multiple compressors receiving both an intermediate pressure vapor injection, and a liquid injection, with the two injection flows being delivered through two distinct passages.
Refrigerant systems are utilized in many applications to condition an environment. In particular, air conditioners and heat pumps are employed to cool and/or heat air entering an environment. The cooling or heating load of the environment may vary with ambient conditions, occupancy level, other changes in sensible and latent load demands, and as the temperature and/or humidity set points are adjusted by an occupant of the environment.
One of the options available to a refrigerant system designer to enhance system performance (capacity and/or efficiency) is a so-called economizer cycle. In the economizer cycle, a portion of the refrigerant flowing from the condenser is tapped and passed through an economizer expansion device and then to an economizer heat exchanger. This tapped refrigerant flow subcools a main refrigerant flow that also passes through the economizer heat exchanger. The tapped refrigerant flow leaves the economizer heat exchanger, usually in a vapor state, and is injected back into the compressor at an intermediate compression point. In an alternate arrangement, a flash tank can be utilized in place of the economizer heat exchanger to provide similar functionality (in essence, the flash tank could be considered as a 100% effective economizer heat exchanger). The subcooled main refrigerant flow exiting the condenser is additionally subcooled after passing through the economizer heat exchanger. The main refrigerant flow then passes through a main expansion device and an evaporator. This main refrigerant flow will have a higher cooling potential because it was additionally subcooled in the economizer heat exchanger. An economizer cycle thus provides enhanced system performance. In an alternate arrangement, a portion of the refrigerant flow is tapped and passed through the economizer expansion device after being passed through the economizer heat exchanger (along with the main flow). In all other aspect this economizer heat exchanger arrangement is identical to the configuration described above.
The economizer function typically includes the tapped refrigerant flow being injected back into compression chambers at an intermediate pressure point.
Another option in refrigerant systems is the injection of liquid refrigerant flow into compression chambers to reduce operating temperature of the compressor and to provide its reliable operation.
Refrigerant systems are known where both the economized vapor and liquid injection are performed. However, the two flows have typically been passed back into a compressor through a single fluid line and internal compressor passages.
However, a compressor designer would like to have the freedom of directing the economized refrigerant to a location that is preferred for the economizer injection function from the performance boost perspective, and at the same time, directing the liquid refrigerant to a location that is preferred for its injection from the reliability enhancement point of view for reduction of the discharge temperature.